Bubble-propelled micro-/nanomotors of variable sizes by regulating the surface microstructure of partially coated Pt shells

Abstract

Bubble-propelled micro-/nanomotors (MNMs) have a strong propulsive force that allows them to operate in harsh environments. However, it is difficult for the current MNMs with size less than 1 μm to exhibit bubble propulsion due to the significantly increasing energy for bubble nucleation with the decrease of their sizes. In this work, we report a simple and scalable colloidal chemistry synthesis method to fabricate bubble-propelled MNMs of variable sizes by regulating the surface microstructure of partially coated Pt shells. Based on the relatively large lattice mismatch between Pt and polydopamine (PDA), Pt nanoparticles are chemically deposited in a dense island-like morphology on the PDA surface of PS–PS@PDA eccentric particles to produce Pt-based MNMs. The as-prepared MNMs have a rough surface of partially coated Pt shells containing plenty of nano-pits, which greatly reduce the energy for bubble nucleation and can act as active sites for the pinning and growth of bubbles. Consequently, the resultant MNMs can demonstrate bubble propulsion even when the size is reduced from about 1 μm down to 200 nm. The result herein provides a facile and plausible strategy to construct small-sized bubble-propelled MNMs, which may extend their applications in environmental remediation and analytical detection to harsh and ultra-miniaturized environments.